Table 3.11 shows 95% of the most frequently occurring
waves in red, hence the sea states in which the system
must remain operational. Yellow plus red text represents
99% of the sea states. The black percentages represent
sea states that were not existent during the measurements.
To fit in the report, the table was obtained by style
modifications from a wave scatter diagram made with
Octopus at the coordinates 138°W 30°N (Chapter 2).
The sea states indicated with black borders are those
that were simulated to determine the most critical sea
state. The selection includes the shortest five wave periods
at each significant wave height within the red area.
When the shortest five wave periods in the red area are
the same for several significant wave heights (for example
the Hs of 2 m versus the Hs of 2.5 m), only the highest
waves were simulated, as they are more critical.
For validation purposes, less extreme wave climates from
the 99% most occurring climates were also chosen. They
may be less critical due to their longer wave period. It is
hypothesized that due to the relatively long wave period,
these sea states will result in the structure being able to
follow the waves properly.
3.5.2.3. Results
The boom assessed here is 1,000 meters long. In order
to assess the results for each wave climate, sea surface
clearance data was recorded at three points along the
length of the boom (Figure 3.55). One at 250 meters from
the mooring at one side, one in the middle at 500 meters
from the mooring and a point at 250 meters from the
mooring at the other side. The dots in Figure 3.55 indicate
the locations of measurement.
To obtain the most probable sea surface clearance with a
three-hour return period, the simulation data is assumed
to be Rayleigh distributed. The average of the maxima
and minima at the three measuring points is used to
compare the simulated wave climates. It should be noted
that the extremes of the sea surface clearance are actually
not Rayleigh distributed. Therefore, these maxima
and minima should not be used for purposes other than
for current comparison.
Tables 3.12 - 3.15 below show the results. The values indicate
the sea surface clearance. The five highest results
are in Tables 3.12 and 33.14, while the lowest results in
Table 3.13 and 2.15 are shown in red.